package utils

import (
	"regexp"
	"strings"
	"unicode"
)

// GenerateSlug converts a string to a URL-friendly slug
// Converts to lowercase, replaces spaces with hyphens, removes special characters
func GenerateSlug(text string) string {
	if text == "" {
		return ""
	}

	// Convert to lowercase
	slug := strings.ToLower(text)

	// Replace spaces and underscores with hyphens
	slug = strings.ReplaceAll(slug, " ", "-")
	slug = strings.ReplaceAll(slug, "_", "-")

	// Remove all non-alphanumeric characters except hyphens
	reg := regexp.MustCompile(`[^a-z0-9-]`)
	slug = reg.ReplaceAllString(slug, "")

	// Remove multiple consecutive hyphens
	reg = regexp.MustCompile(`-+`)
	slug = reg.ReplaceAllString(slug, "-")

	// Remove leading and trailing hyphens
	slug = strings.Trim(slug, "-")

	// If empty after processing, return a default
	if slug == "" {
		slug = "item"
	}

	return slug
}

// IsValidSlug checks if a string is a valid slug format
func IsValidSlug(slug string) bool {
	if slug == "" {
		return false
	}

	// Check if it contains only lowercase letters, numbers, and hyphens
	reg := regexp.MustCompile(`^[a-z0-9-]+$`)
	if !reg.MatchString(slug) {
		return false
	}

	// Check it doesn't start or end with hyphen
	if strings.HasPrefix(slug, "-") || strings.HasSuffix(slug, "-") {
		return false
	}

	// Check it doesn't have consecutive hyphens
	if strings.Contains(slug, "--") {
		return false
	}

	return true
}

// CleanString removes leading/trailing whitespace and normalizes spaces
func CleanString(s string) string {
	// Trim whitespace
	s = strings.TrimSpace(s)

	// Replace multiple spaces with single space
	reg := regexp.MustCompile(`\s+`)
	s = reg.ReplaceAllString(s, " ")

	return s
}

// ContainsOnlyLetters checks if a string contains only letters (and spaces)
func ContainsOnlyLetters(s string) bool {
	for _, r := range s {
		if !unicode.IsLetter(r) && !unicode.IsSpace(r) {
			return false
		}
	}
	return true
}